The use of nalmefene for intrathecal opioid-associated nausea in postpartum patients

The aim of this study was to compare the severity of nausea and incidence of emesis in laboring parturients who received intravenous nalmefene or placebo following an intrathecal opioid (ITO). We randomly assigned 60 ASA class I or II multiparous women to receive nalmefene or placebo. Subjects received fentanyl, 25 micrograms, and morphine, 250 micrograms, intrathecally on request for analgesia. Thirty minutes after vaginal delivery, the experimental group received nalmefene, 20 micrograms, and the placebo group received an equivalent volume of normal saline intravenously. Visual analog scale nausea scores and data about episodes of emesis were obtained during labor and during the first 24 hours postpartum. There were no significant differences in age, weight, duration of labor, volume of intravenous fluids infused, time from last meal to delivery, or time from administration of the ITO to injection of the study drug. There were no significant differences in mean visual analog scale nausea scores or frequency of emesis for any time interval. Nalmefene, 20 micrograms, given intravenously within 30 minutes of vaginal delivery does not significantly reduce the nausea and vomiting associated with the use of ITOs for labor analgesia.